Embryo measurements dating
These measurements are more appropriately used in the assessment of fetal growth, particularly in the second half of the pregnancy, than in the assessment of gestational age.It is, however, an appropriate measurement in the second trimester to demonstrate normal fetal proportions.
At any gestation, if the ultrasound fetal measurements of each parameter are not in agreement, the reason for this difference should be evaluated.The accuracy rate is very low, many women are pressured into interventions that do more harm than good, and even the mere PREDICTION of macrosomia (large baby) alters the way physicians perceive and treat labor.A number of studies have questioned the use of ultrasound for estimated fetal birth weight.The abdominal circumference is measured at the level of the liver and stomach, including the left portal vein at the umbilical region.If we assume a fetus is growing normally, biometric measurements are determined by gestational age, and we can estimate the gestational age and thus the due date.The strong acoustic shadow behind the femoral or humeral shaft and the visualisation of both cartilaginous ends indicates that the image plane is on the longest axis and is the optimal measurement plane.
The calipers are placed along the diaphyseal shaft excluding the epiphysis.
BPD - OFD - HC | Femur and Humerus (FL HL) | Abdominal Circumference (AC) Fetal Weight Percentile Charts | Fetal Growth Percentile Charts Measurement Standards | Ultrasound Measurement Chart | Crown-Rump Length After the first trimester of pregnancy a multiparameter assessment of gestational age is advocated.
This should include at least two fetal measurements (usually biparietal diameter (BPD) and femur length (FL)) plus a consideration of additional parameters such as head circumference (HC), occipitofrontal diameter (OFD), abdominal circumference (AC) and humerus length (HL).
Percentile Example: Out of 100 babies, a reading of forty percent (this is the percentile value) indicates that the baby is smaller than sixty other babies and larger than forty other babies. A value that reads below 50% indicates that the measurement is lower than the average.
Thus, a value that is above 50% indicates that the measurement is above average.
Since all of these measurements are strongly related to gestational age, it is not usually important how they are combined.